1. Field of the Invention
The present invention relates to a developer collecting apparatus and an image forming apparatus having the developer collecting apparatus.
2. Description of the Related Art
In recent years, it has been gradually more common in an image forming apparatus to shift printing in black and white to printing in full color. Moreover, along with development of the image forming apparatus, a color image forming apparatus has been utilized for general purposes. Among the color image forming apparatuses, especially for an image forming apparatus which employs an electrophotographic system, an indirect transfer system has been often proposed in an attempt to meet miniaturization of the apparatus and speeding up of color image formation. The indirect transfer system is characterized by the following processes in formation of a color image onto recording paper. Firstly, a developer image is formed (first transfer) by stacking image information separated in color for each color component from an electrostatic latent image bearing member (hereinafter may be referred to as a photoreceptor) respectively provided on a plurality of image forming units (also referred to as a process printing unit) onto an intermediate transfer body. And then, the developer image processed by the first transfer is totally transferred (second transfer) onto the recording paper serving as a transfer-subjected medium.
In general, it is well known that, when the first transfer is carried out from a photoreceptor to an intermediate transfer body at a transfer step in the image formation, not all the developer which forms a developer image on the photoreceptor is transferred onto the intermediate transfer body, but a little developer remains on the photoreceptor. It is known that a transfer efficiency of the first transfer is approximately 90%. Also at a second transfer step for transferring the developer image on the intermediate transfer body onto the recording paper, residual developer is generated as in the above case.
Consequently, the image forming apparatus is usually provided with a cleaning apparatus for collecting the residual developer remaining on the photoreceptor and the intermediate transfer body at the first and second transfer steps and in addition, a developer collecting apparatus for collecting as waste developer the residual developer which has been cleaned by the cleaning apparatus. However, in order to provide a plurality of the developer collecting apparatuses for a plurality of the image forming units and the intermediate transfer body, a larger space in the apparatus will be necessary therefor, which is not favorable in terms of compact design, decrease of user's operability, and pollution inside the apparatus due to the waste developer.
In consideration of the above points, the applicant has proposed an integrally-formed developer collecting container for accommodating waste developer generated from a plurality of residual developer sources in Japanese Patent Application No. 2004-335499 so as to solve the above problems.
In the above proposal, integration of the container is realized, and problems for compact design or the like can be solved. However, there arises a problem that even when an amount of the waste developer accommodated in a waste developer container does not reach a capacity (this capacity is hereinafter referred to as a full state), a drive for rotating stirring member for stirring the waste developer accommodated in the waste developer container stops so that the stirring member is locked. Moreover, the drive for rotating the stirring member stops before the waste developer container becomes full of the waste developer, and as a result, it is not possible to collect the waste developer even when the waste developer container is not filled up with the waste developer. This leads to a problem that an image forming operation is forced to stop in order to prevent the pollution inside the apparatus and pollution on the image caused by the waste developer which cannot be collected.
In a related art, a photosensor is utilized for determining whether or not the waste developer container is filled up with the waste developer (for example, refer to Japanese Unexamined Patent Publication JP-A 2003-345203). In the art disclosed in JP-A 2003-345203 is provided a detecting switch for detecting whether or not a waste toner box serving as a waste developer container is mounted on an apparatus main body, and a photosensor which operates either in a translucent state or in a light shielding state when the detecting switch is turned on while the photosensor is brought to the same state as the translucent state when the detecting switch is turned off. When the detecting switch is turned on and the photosensor is in the light shielding state, it is determined that the waste toner box is filled up with the waste developer.
However, the art of JP-A 2003-345203 includes a problem that significantly careful check is required for the switches or the like, in order to determine whether the waste toner box is mounted and full with waste developer or the waste toner box is not mounted but a signal indicating a full state is outputted, because the photosensor is brought to the same state as the translucent state even when the detecting switch is turned off, specifically when the waste toner box is not mounted on the apparatus main body.
Further, the method of detecting an accommodated amount of the waste developer in the waste toner box through the photosensor may lead false detection since the waste toner accumulated in the container is excellent in fluidity, with the result that the waste toner contaminates an inner wall portion of the container due to flowing of the waste toner inside the container, which leads decrease of detecting accuracy of the photosensor. Furthermore, a first notice is suddenly given by the detection through the photosensor when the waste toner box is filled up with the waste developer, with the result that there arises a problem that the image forming operation is forced to stop during image formation in order to replace the waste toner box.